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Shutterless optically stabilized capnograph

  • US 5,095,913 A
  • Filed: 05/11/1990
  • Issued: 03/17/1992
  • Est. Priority Date: 09/01/1989
  • Status: Expired due to Term
First Claim
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1. A device for detecting the concentration of a gaseous component of a substantially gaseous flow stream, comprising:

  • (a) a source of infrared radiation;

    (b) a pair of physically separate infrared detectors disposed on the same substrate so as to receive incident radiation from said infrared radiation source and to produce electrical signals representative of the received incident radiation;

    (c) means for directing at least a portion of said substantially gaseous flow stream between said detectors and said infrared radiation source;

    (d) attenuating means, disposed between only one of said detectors and said directing means, for attenuating the incident radiation impinging upon only said one detector; and

    (e) means for processing said electrical signals representative of the received incident radiation so as to produce an optically stabilized signal substantially unaffected by changes in the ambient temperature of the environment in which said device operates.

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